1. Field of the Invention
This invention relates to medical instrumentation for tissue ablation. More particularly, this invention relates to treating cardiac arrhythmias by ablating in a vicinity of pulmonary venous tissue.
2. Description of the Related Art
It is now well-known that atrial fibrillation can be triggered by aberrant conduction pathways that originate in muscle bundles that extend from the atrium to the pulmonary veins and that ablation in order to produce electrical pulmonary vein isolation ablation can maintain sinus rhythm.
Contact force methods are effective in accomplishing circumferential pulmonary vein isolation. For example, commonly assigned U.S. Pat. No. 6,997,924 to Schwartz et al, which is herein incorporated by reference, describes pulmonary vein isolation using high energy emission of laser light energy. After transseptal advancement of a catheter to the ostium of a pulmonary vein, an anchoring balloon is expanded to position a mirror near the ostium of the pulmonary vein, such that light energy is reflected and directed circumferentially around the ostium of the pulmonary vein when a laser light source is energized. A circumferential ablation lesion is thereby produced, which effectively blocks electrical propagation between the pulmonary vein and the left atrium.
More recently hybrid catheters having contact force sensors and location sensors have been employed to isolate the pulmonary veins electrically, such as the Smart Touch™ catheter. However, residual conduction gaps may remain in some patients despite optimal ablation.